Electric signal recording blank



May 6, 1969 FIG. 4

H. R. DALTON ELECTRIC SIGNAL RECORDING BLANK Filed Aug. 16, 1965MHSKlA/G CON f//VG INVENTOR.

#420.10 A? 0,44 roA/ United States Patent O 3,442,699 ELECTRIC SIGNALRECORDING BLANK Harold R. Dalton, 931 Rydal Road, Jenkintown, Pa. 19046Filed Aug. 16, 1965, Ser. No. 479,904 .Int. Cl. B44d 1/18, 1/14; H01!)1/04 U.S. Cl. 117-201 25 Claims ABSTRACT F THE DISCLOSURE This inventionrelates to recording blanks, and more particularly to multiple ormultilayer blanks for recording electric signals such as facsimilesignals and the like. More specifically the invention is that of such anelectric signal recording blank having a relatively light-colored outeror masking layer throughout which there is distributed nely dividedparticles of a ferroelectric or ferromagnetic material or a mixture ofany of these high dielectric constant materials. Inclusion of the highdielectric constant material in these recording blanks provides not onlyimproved recordings but also improved operation particularly with themultiple recording electrodes or styli in systems employing a pluralityof them.

The facsimile recording art uses in general two types of recordingblanks, (a) the photographic type and (b) the direct recording type. Thephotographic blank has the disadvantage that the recording machine mustbe operated under dark room conditions, and comparitively relativelyexpensive photographic developing equipment and operations are requiredto provide a complete record.

The direct recording blank may be divided into four groups, pressuresensitive, electrolytic, electrostatic, and dry electronic. Except forthe photoconductive electrostatic recording blank, the direct recordingblanks can be used under normal light conditions and the record isimmediately and permanently produced as the electric signals are beingreceived.

One kind of heretofore found useful direct recording blank comprises abacking or web of paper having applied to it a white masking coatingwhich is removable and/ or decomposable in localized areas in responseto applied electric signals, so as to expose the under surface which isblack and electrically conductive.

Thus, in one known such blank, the paper backing itself is renderedelectrically conductive to a predetermined degree by having incorporatedin it a conductive material such as powdered carbon or carbon black. Inanother known blank, the paper backing can be any usual kind of paperhaving one of its surfaces treated or coated with a conducting materialconsisting to a great extent of carbon black, to give it the necessaryelectrical conductivity and blackness for contrast.

In either of these two types of blanks, the black conductive or undersurface is masked by the white masking coating. It is the maskingcoating which responds to the applied electric signals, so that in thetelefacsimile art the recording is effected by those signals acting onand causing the removal of successive elemental areas, Ifor eX- ample,of about 0.01 square inch each, of that coating.

ice

Heretofore, the masking coating had its color contrast with the blackunder surface, by the incorporation in the former of a conventionalwhite pigment such as titanium dioxide, zinc oxide, zinc sulfide,lithopone, copper thiocyanate, photo-conductive phosphors,electricallyconductive zinc oxide, and the like, in its binder such ascellulose esters or ethers, acrylic resins, polyvinyl chloride-acetateresins, polyvinyl butyral resins, etc.

These prior recording blanks depend for their operation on theelectrical field of the signal voltage applied to the stylus attaining avalue such that electronic breakdown of the coatings occurs or thecoating may be removed and the signals effect -made visible as a resultof the thermal degradation of the coatings; or both the phenomenon ofelectronic breakdown and thermal degradation may operate simultaneously.

In order to give some divergence to the electrical field at the point ofthe stylus it was found necessary for good signal reproduction toincorporate in the masking coating a pigment having slight electricalconductivity. This was done by using the photoconductive phosphors,light colored semiconductor pigments, electrically-conductive zincoxide, and meta-stable compounds like mercuric sulfide.

While coatings containing pigments of this type function well in someapplications, recording blanks made using them give very poor results orare inoperative when used on equipment of the multiple styli type. Forexample, signals impressed on two or more adjacent styli simultaneouslydo not record. Then also, decomposition products collect back from thestyli tips during the recording process. These undesirable productseventually accumulate to the extent that they bridge the gap betweenadjacent styli, resulting in poor signal response or complete failure.

It was found that (l) much clearer and sharper recordings are provided,and particularly in facsimile systems using a plurality of styli, andthat failure to obtain recordings between adjacent styli is avoided andother disadvantages are overcome, by the recording blank of theinvention, in which blank (a) there is dispersed in its masking layerfinely divided particles of (i) one or more ferroelectric and/orferromagnetic materials, or (ii) these ferroelectric and/or-ferromagnetic materials together with a quantity of an electricallynonconducting pigment such as zinc oxide or sulfide or others asexemplified hereinabove, and (b) that layer overlies an electricallyconducting layer composed of a continuous film or sheet having dispersedin it electric conducting material such as finely divided carbon orcarbon black; and (2) considerably reduced collection of breakdownproducts occurs on the styli.

Thus, a feature of the invention is its making available an improvedrecording blank which responds to stylus applied signals to yield muchclearer and sharper recordings, and particularly in systems employingmultiple styli such as printing apparatus wherein the styli formcharacters as a matrix of dots produced by an electric field or passageof an electric current through the blank. These multiple styli may bearranged uniformly spaced in a single row -or in two or more rows in anydesired spacing pattern between rows.

A further feature of this invention is its provision of a recordingblank or sheet which yields clear and sharp fine dots from signalsimpressed upon selected styli (arranged in columns or rows) with littleor no irregularity in the form of the individual dots even though asignal may be impressed simultaneously upon two adjacent closely spacedstyli.

A further feature is its provision of a recording blank having a maskingcoating whose decomposition products produced during the recording onthe blank have a greatly reduced tendency t-o collect on the recordin-gstyli, so that they thus avoi-d interfering with the resolution andaccuracy of the recorded subject m-atter.

Still another feature of the invention lies in its recording blankswhich are made up of one or more electrosensitive coatings and/or layerswhich retain their chemical, physical and electrical propertiesregardless of changes in the ambient atmosphere.

Yet a further feature of the invention resides in its novel facsimilerecord-ing blank comprising a carrier or supporting base or web ofpaper, cardboard, foil, or similar sheet material, on which is depositedone or more continuous layers or coatings of a film-forming plastic orresin or elastomer, having incorporated in it electrically conductiveparticles and over which is applied a single white or light coloredlayer or coating containing a ferroelectric and/or ferromagneticmaterial, or mixtures of either or both of these high dielectricconstant materials.

The ferroelectric materials are defined herein as materials having theperovskite structure, visualized as a spacefilling array of truncatedcubes and octahedra, and exemplified by barium titanate, calciumtitanate, strontium titanate, the high dielectric constant zirconates,gallates, colombates, and tantalates, or mixtures of any of them, etc.;and characterized by their having a dielectric constant of from about l0to about 10,000.

The ferromagnetic materials are defined herein as materials havingcrystalline structure similar to that of the mineral spinel derived lbyreplacing the ferrous ion of magnetite with any of the divalent ionsmagnesium, manganese, cobalt, nickel, copper, zinc or cadmium, etc.; andmay consist of mixtures of two or more of these individual ferrites; andare characterized by their having a dielectric constant of from about lto about 500,000.

Although one should not be held to any particular theory as to theoperation of the masking coating included in the invention, it isbelieved that the effect of the alternating field of the carrier signalon the masking dielectric layer of ferroelectric and/or ferromagneticmaterial causes a current to flow as a -result of periodic displacementof the dipole charges on that material. This displacement current may beconsidered to be directly proportional to the dielectric constant of thedielectric layer, under a given field strength and frequency.

A masking coating, made according to the invention, with a ferroelectricor ferromagnetic material having, for example, a dielectric constant ofsay 5,000 gives very good recording results. It is difficult to say whatthe minimum dielectric constant should be for optimum results. That isso because it is difficult to prepare such coatings formulated to anexact value, and also results depend on the carrier frequency used. Itappears, however, that the minimum value for the dielectric constant ofthe masking coating for good results is much greater than 8, exceeds 9and is of the order of l0 when used with a carrier frequency of 15,000cycles per second. One skilled in this art readily can conduct thenecessary tests to select a formulation from within the scope of thedisclosure herein and its various examples to compound a suitablemasking coating formulation and from it to prepare such a coating toapproach the approximately optimum results for the specific carrierfrequency to be used in a particular operation.

Direct current pulses impressed upon styli in contact with maskingcoatings of this invention also will result in good signal response,provided the coatings are applied to an electrically conductive basesheet; or if applied to a base conductive coating on a nonconductivesupport, a ground connection to the conductive coating must be made forbest results.

The recording blanks of the invention are illustrated by, but notrestricted to, the several embodiments shown in vertical cross-sectionin the first four of the accompanying drawings wherein:

FIG. l exemplifies a broad form having an electrically conducting paper10 or base sheet as its carrier support and adheringly applied on itsupper surface the masking coating 12;

FIG. 2 is a modified form of that FIG. 4l, by having separate conductinglayer 11 interposed between the electrically conducting paper 10 and themasking coating 12;

FIG. 3 is a modified form of that of FIG. 2, by having a nonconductingpaper 14 as its base sheet or carrier support instead of the conductingpaper 10 of FIG. 2;

FIG. 4 is a modified form of that of FIG. 3, by having an intermediatec-onducting coating or layer 15 interposed between its conductingcoating 11 and masking coating 12; and

FIG. 5 is a schematic showing of a facsimile system employing aplurality of styli from which discharges the electric signals (from thetransmitter picked up by the receiver) against an elongated recordingblank 16 of this invention. The person of ordinary skill in this artknows the make-up and operation of such apparatus system using multiplestyli with a so-called dry recording blank. Thus, it only need be statedthat signals corresponding to the scanned intelligence to be transmittedgo from the transmitter to the receiver and in turn through usualconductors to the respective individual styli 17, corresponding to whatis being transmitted at each different instant, and with the resultingcorresponding dots being formed in the masking layer 12 of the recordingblank 16 as it moves past the styli 17 at its set rate in synchrony withthe sending rate from the transmitter.

'Many of the ferroelectric materials applicable in the improved maskingcoating or layer of the recording blanks of the invention have a lightenough color to provide adequate contrast with the various finelydivided carbon or carbon black containing conductive coatings or layers,for such ferroelectric material to be used as the sole particulateingredient of the masking layer. However, some of the ferroelectricmaterials have too dark a color and most of the ferromagnetic materialshave a very dark hue, so that a masking coating made from such darkermaterials may not provide adequate contrast in use.

Any inadequate contrast from such relatively too dark ferroelectricand/or ferromagnetic materials can be enhanced and its inadequacyovercome by incorporating with them a quantity of an electricallynonconducting white or other light colored pigment, such as zinc oxide,zinc sulfide, or titanium dioxide, sufficient to form an adequatelylighter colored blend that will provide a sufficiently light coloredmasking coating which will yield adequate contrast.

The generally dark color of the ferromagnetic materials would appear torestrict somewhat their use in a masking coating for a recording blankof the invention, due to inadequate contrast when they are to be usedalone. However, such restriction is offset to a large extent by theirgenerally much higher dielectric constant so that considerably less ofsuch ferromagnetic material would be required for a given result.

Such initially indicated restriction is offset further by the earlierabove described blending with a white or light colored pigment. Thus,facsimile recording blanks of the invention having good recordingproperties can be made even with as little as 5% of such ferroelectricor ferromagnetic material in the blend with such nonconductive pigment.In some instances a dark ferromagnetic material might be blended with asuitable amount of some adequately lighter ferroelectric material.However, such recording blanks with very satisfactory recordingproperties have been made with very much higher content of theferroelectric material in any such blend and even with of theparticulate particles in the masking coating being ferroelectricmaterial.

The various embodiments and modifications of the recording blank of theinvention can be prepared by methods known to those of ordinary skill inthis art, for example, as by the methods described in my U.S. Patent2,664,043 (particularly its columns 3-8) including the preparation ofthe masking layer or coating. Such latter can be prepared by the stepsof the method procedure for the masking coating in that patent (lastparagraph of each of its columns 5 and 6 and first paragraph of column7). That patent describes also methods of adheringly applying thevarious layers or coatings over one another and to a suitable backingweb or support or carrier sheet, as well as applicable coating weightsto be used.

Thus, formulations for preparing the masking coatings of the recordingblanks of the invention, by the just above indicated procedures, areillustrated by, but not restricted to, the following:

Example 1.-Masking coating formulation Weight (lbs.) Barium titanate(ferroelectric: 63.7% BaO, 33.2%

TiO2, dielectric constant 1200 at 1000 cycles/sec.) 130 Zinc sulfide 50Zinc oxide (particle size 0.25 micron) 50 Nitrocellulose, 1/2 sec.viscosity 25 Ethylcellulose, 10 centipoises viscosity 20 Tricresylphosphate 35 Solvent (30% butyl acetate, 50% toluene, 13%

ethanol, 7% butanol) 200 Example 2.--Masking coating with quite highdielectric constant ferroelectric material Barium strontium titanate(ferroelectric: cation content 79% barium, 21% strontium; dielectricconstant 8500 at 1000 cycles/sec.) 30 Zinc sulfide 10 Polyvinyl butyral(approximate mol. wt. 10,000) 6 Methanol 120 Example 3.-Masking coatingwith quite high dielectric constant ferroelectric material, Withoutcolor diluting pigment Barium strontium titanate (ferroelectric: cationcontent 79% barium, 21% strontium; dielectric constant 8,500 at 1,000cycles/sec.) 45 Polyvinyl butyral (approximate mol. wt. 10,000) 6Methanol 120 Example 4.-Masking coating with very high dielectricconstant ferromagnetic material in a latex system Zinc ferrite(ferromagnetic material: dielectric con- The foregoing examples, andsuitable modifications of them within the scope of the disclosure, areapplicable for the preparation of masking coatings includingferroelectric and ferromagnetic materials, according to this invention.However, use of these high dielectric constant materials is not to beconfined solely to the masking coating. As part of the invention, any ofthese ferroelectric and ferromagnetic materials and mixtures of any ofthem can provide even somewhat superior recording results, compared tothose obtained from their use in the top or masking coating alone, whenthey are included along with the carbon or carbon black used in aso-called intermediate or second conductive 0r conducting coating therecording blank, similar to the intermediate or second such coatingdisclosed in my aforesaid U.S. Patent 2,664,043 (as in its column 4first full paragraph).

Example 5 Weight (lbs.) Zinc ferrite, cobalt ferrite (ferromagneticmaterial:

dielectric constant 400,000 at 1,000 cycles/sec.) 30 Acetylene black 3Vulcan C (carbon black product of Cabot Corp.) 20 Butyl methacrylatepolymer (product of E. I. du

Pont de Nemours Co.) 200 Toluene 1000 The specific ferroelectrictitanate of any of the preceding Examples l, 2 and 3 can be replaced inpart or as a whole by a correspondingly equivalent quantity of any othersuch high dielectric constant alkaline earth (magnesium being includedwith them) titanate such as calcium and/or strontium titanate, or by anyother high dielectric constant ferroelectric material having adielectric constant of at least about 10, for example, such zirconate,gallate, colombate, or tantalate, or others, or mixtures of any of them,or by any such ferromagnetic materials as any of the type hereinabovedescribed or disclosed, for example, any ferrite such as those used ineither of the Examples 4 and 5.

Likewise, the specific ferromagnetic ferrite of either of Examples 4 and5 can be replaced in part or as a whole by a correspondingly equivalentquantity of a single or mixed ferrite such as any hereinabove describedor specifically disclosed, or of any other high dielectric constantferromagnetic material having a dielectric constant of at least aboutl0, or similarly by any ferroelectric material having such dielectricconstant.

Then too, the nonconductive pigment zinc sulfide, or mixtures of it andzinc oxide, of any of these examples, can be replaced in part or as awhole by a quantity sufiicient to give the needed or desired contrast,of any other compatible nonconductive light colored to white pigmentsuch as any specifically disclosed or broadly described hereinabove, oreven by a light colored to white conducting pigment so long as theferroelectric and/or ferromagnetic material is present to the extent ofat least 5% of the particulate content of the coating so as still toprovide the herein disclosed effect of its high dielectric constantcharacter.

In like manner, any of the film-forming materials such as the specificpolymer or plurality of polymers of any of the Examples 1 through 5 canbe replaced in part or as a whole by any other compatible suitablefilm-forming material, so long as the proportion of content of the highdielectric constant material and any contrast-improving pigment admixedwith it to the film-forming material is such as to provide a suitablyfluid and suliiciently spreadable coating mixture with the particularsolvent or dispersing liquid used to apply a sufiiciently adherentcontinuous coating layer; all as more fully explained in the abovereferred to portions of my U.S. Patent 2,664,043.

In the same way, the plasticizer tricresyl phosphate of Example 1 or thedispersant of Example 4 can be used when needed and compatible in any ofthe other examples, or can be replaced in part or as a whole by anyother respective and compatible plasticizer and/or dispersant.

Then by selecting the desired backing or support base or sheet andapplying to it the desired masking coating if the backing base is, forexample, a conducting paper, or whether it is conducting ornonconducting, applying over it in sequence the desired arrangement ofrespective conducting coating or coatings and final masking coating,there are prepared by the procedure described in the aforesaid U.S.Patent 2,664,043, the following illustrative, but not to be consideredas limiting, examples of recording blanks:

(i) A recording blank having a conductive paper supporting base withparticulate carbon black incorporated in it, and adhesively superposedon one of its surfaces a masking coating such as that of any of theExamples 1 through 4 or of any of the described modifications of them.

(ii) A recording blank having as its supporting base a continuous sheetor web of the conducting paper, as used in the just preceding example,and sufficiently adhesively applied to one of its surfaces any carbonblack containing conducting coating such as any shown in U.S. Patent2,664,043, and similarly adhesively applied to the latter a maskingcoating of any of the examples 1 through 4 or the describedmodifications of any of them.

(iii) A nonconducting supporting base such as a relatively thin butsufiiciently strong sheet or web of nonconducting paper or plastic film,and similarly applied to one of its surfaces a conducting coating suchas described in the just preceding recording blank, and applied to theouter surface of the latter a masking coating of any of the Examples lthrough 4 or of any of the described modifications of any of them.

(iv) A nonconducting supporting base such as that used in the justpreceding recording blank, and applied to one surface of it a conductingcoating such as described in the same preceding blank, applied to theouter surface of the latter an intermediate conducting coating ofrelatively similar composition to that of any described in said Patent2,664,043; and applied to the outer surface of the latter a maskingcoating such as that of any of the Examples l through 4 or any of theirvarious indicated modifications.

(v) A recording blank can be prepared by replacing the intermediateconducting coating of the just preceding example (iv) by a conductingcoating having incorporated in it high dielectric constant material,such as that of Example 5 or any of the various described possiblemodifications.

What is claimed is:

1, A multilayer recording blank responsive to stylus applied electricsignals, which comprises:

(i) a layer rendered electrically conductive by having a sufficientamount therefor of electrically conductive carbon incorporated in it,and

(ii) adherently affixed to one surface of said electricall ly conductivelayer a masking coating layer comprising:

(a) a such layer-forming organic material prone to breakdown responsiveto said stylus-applied signals at their points of application, and

(b) incorporated in said layer-forming organic material nely dividedmetal compound particles from about 5 to 100 percent of which isdielectric material selected from ferroelectric material, ferromagneticmaterial, or mixtures of any of them; said finely divided particlesbeing so proportioned to the layer-forming material to enable it tomaintain its continuity and adherence to said electrically conductivelayer and also to provide a readily visually discemable contrast withthe dark appearance of said masking layer at its respective breakdownpoints after application of electric signals thereto; and when saiddielectric material is less than 100 percent of said particles, thebalance is a pigment different from said dielectric material.

2. A recording blank as claimed in claim 1, which includes solely (i)said masking coating and (ii) the electrically conductive layer and thelatter is the backing support sheet of said recording blank.

3. A recording blank as claimed in claim 1, which includes solely (i)said masking coating, (ii) said electrically conductive layer as thebacking support sheet of said blank; and (iii) an electricallyconductive coating Ibetween (i) and (ii).

4. A recording blank as claimed in claim 1, which includes solely (i)said masking coating, (ii) an electrically nonconductive layer as thebacking support sheet of said blank; and (iii) said electricallyconductive coating between (i) and (ii).

5. A recording blank as claimed in claim 4, which has (iv) anintermediate electrically conductive coating between its masking coatingand its electrically conductive coating.

6. A recording blank as claimed in claim 5, wherein said intermediateconductive coating also contains a quantity of dielectric materialselected from ferroelectric material, ferromagnetic material, ormixtures of any of them.

7. A recording blank as claimed in claim 1, wherein the dielectricmaterial is a ferroelectric.

8. A recording blank as claimed in claim 7, wherein said ferroelectricmaterial is an alkaline earth titanate.

9. A recording blank as claimed in claim 8, wherein said titanate is abarium titanate.

10.' A recording blank as claimed in claim 9, wherein the ferroelectricmaterial is barium titanate.

11. A recording blank as claimed in claim 9, wherein the ferroelectricmaterial is barium strontium titanate.

12. A recording blank as claimed in claim 1, wherein the dielectricmaterial is a ferromagnetic material.

13. A recording blank as claimed in claim 12, wherein the ferromagneticmaterial is a ferrite.

14. A recording blank as claimed in claim 13, wherein the ferrite iszinc ferrite.

15. A recording blank as claimed in claim 1, wherein the differentpigment material is electrically nonconductive.

16. A recording blank as claimed in claim 15, wherein the differentpigment material is selected from zinc oxide, zinc sulfide, titaniumdioxide, copper thiocyanate or lithopone, or mixtures thereof.

17. A recording blank as claimed in claim 16, wherein said pigmentmaterial is a mixture of zinc oxide and zinc sulfide.

18. A recording blank as claimed in claim 17, wherein the dielectricmaterial is a ferroelectric material.

19. A recording blank as claimed in claim 18, wherein the ferroelectricmaterial is an alkaline earth titanate with a dielectric constant of atleast 10.

20. A recording blank as claimed in claim 19, wherein the titanate is abarium titanate.

21. A recording blank as claimed in claim 17, wherein the dielectricmaterial is a ferromagnetic material.

22. A recording blank as claimed in claim 21, wherein the ferromagneticmaterial is a ferrite.

23. A recording blank as claimed in claim 22, wherein the ferrite iszinc ferrite.

24. A multilayer recording blank responsive to stylus applied electricsignals, which comprises:

(i) a layer rendered electrically conductive by having a sufficientamount therefor of electrically conductive carbon incorporated in it,and

(ii) adherently aixed to one surface of said electrically conductivelayer a masking coating layer comprising:

(a) a such layer-forming organic material prone to breakdown responsiveto said stylus-applied signals at their points of application, and

(b) incorporated in said layer-forming organic material finely dividedmetal compound particles of dielectric material selected fromferroelectric material, ferromagnetic material, or mixtures of any ofthem; said finely divided particles being so proportioned to thelayer-forming material to enable it to maintain its continuity andadherence to said electrically conductive layer and also to provide areadily visually discernable contrast with the dark appearance of saidmasking layer at its respective breakdown points after application ofelectric signals thereto.

25. A system for recording marks and characters from facsimile signalstransmitted by a facsimile transmitter scanning such .marks andcharacters to be transmitted, which system comprises a facsimilereceiver having at least one stylus for applying from its tip electricaldischarges provoked by said signals, a cathodically grounded surfacecapable of supporting a recording blank thereon, and supported on saidsurface a recording -blank as claimed in claim 23 and with its maskingcoating facing said at least one stylus and with the tip thereofadjacent said surface to enable electric signals applied therefrom tobreakdown the organic material of said coating at localized areasthereon corresponding to like areas on the material being transmitted.

References Cited UNITED STATES PATENTS 2,643,130 6/1953 Kornei 346-135 X2,664,044 12/ 1953 Dalton 117-69 X 2,941,901 6/1960 Prill et al. 346-135X 3,007,807 11/1961 Radocy 117-66 3,139,354 6/1964 Wolff 252-62.62

ALFRED L. LEAVITI, Primary Examiner.

ALAN GRIMALDI, Assistant Examiner.

U.S. Cl. X.R.

